1. Field of the Invention
This invention relates to filters for sterile filtration of fluids, and more particularly, to a filter case construction for such filters in which means is provided to prevent leakage of medium to be filtered from an inlet into the filtrate chamber. In copending application Ser. No. 158,790, filed concurrently herewith, leak detecting means is disclosed for detecting leakage of non-filtered medium.
2. Prior Art
U.S. Pat. No. 3,298,522 is made of record.
In a known filter case the inlet connection piece for the medium to be filtered is undetachably connected with the base plate; it penetrates the intermediate plate, and ends in the top part of the case. The filtrate space below the intermediate plate is sealed off against the top part of the case in the area of the connection piece by at least one O-ring packing, arranged on the inside of the perforation in the intermediate plate or on the outside of the tubular inlet connection piece. At filtration under high pressure, the packings of replaceable structural elements or of the filter cartridges sometimes become loose. This is partly caused by damage to the packing rings, and partly by a canting of the structural elements. In the known case, unfiltered medium flows or leaks from the top portion of the case along the packing and the outer edge of the inlet connection piece into the filtrate space, the leaky spot remaining undeterminable. In sterile filtration, a non-sterile medium thus enters the sterile space, whereby the whole filtrate becomes non-sterile.